Robbing banks a bad idea for crooks from economic standpoint

Bonnie Parker and Clyde Barrow were famous for robbing banks, but they never… (AFP / Getty Images )

Crime doesn't pay, at least not very well, when it comes to robbing banks, a new study finds. With unprecedented access to financial data from British banks, economists have shown that bank robbers don't make a lot of money, certainly not enough to justify the risks involved in such an armed robbery. "The return on an average bank robbery is, frankly, rubbish," the researchers wrote in the statistics journal Significance. "It is not unimaginable wealth." It is so low, in fact, that it is not financially worthwhile for banks to install screens that could further reduce robberies.

Economist Neil Rickman of the University of Surrey and his colleagues were given unusual access to financial data from the British Bankers' Assn. Such data about robberies are not normally disclosed to the public because it is commercially sensitive and could potentially encourage copycat robbers. Treating bank robbery as a business like any other, they used normal statistical measures to calculate profitability.

In 2007, there were 106 bank robberies or attempted robberies at the 10,500 bank branches, compared with 7,500 robberies of other businesses. (In the U.S. in 2006, there were about 12,000 bank robberies.) Although bank robberies in Southern California tend to occur in higher numbers at branches near freeway entrances, the British team found no link to branch size, branch location, or how busy a particular branch is. Of all those robbed, only 13 were targeted twice and only one three times. About a third of attempted robberies were unsuccessful, and about 20% of the successful robbers were ultimately caught and convicted.

The average take in a British bank robbery is a modest 12,706.60 euros (about $15,887) per person, compared with an average of $4,330 in U.S. bank robberies. Given that the average U.K.wage for fully employed people in Britain is about 26,000 euros, a bank robbery "will give him a modest lifestyle for no more than 6 months." If he robs two, he will still have only a modest lifestyle. Four robberies, and the odds are excellent that he will land in jail. "As a profitable occupation, bank robbery leaves a lot to be desired," the authors wrote. (A similar analysis of drug dealing in the book "Freakonomics" explains why most low-level dealers live with their mothers: The activity is so unprofitable that they cannot afford a place of their own.) That may be why bank robberies are declining in the U.K. and the U.S.

Using a firearm in the robbery increases the average take by 10,300 euros (nearly $13,000). Each additional member of the gang raises the take by 9,033 euros ($11,600), but that means the average take per robber is lower.

Some banks in England, but not in the U.S., have fast-rising metal screens that can be deployed in a robbery to separate the robbers from staff. Such screens reduce the probability of a successful robbery by 32.2 percentage points. Given that only 66% of robberies are successful, the screens could reduce the success rate by half, the authors write. But given the low take from the robberies and the high cost of the devices, such countermeasures are not economically reasonable, they say. Such calculations, however, do not include the psychological effects of robberies on bank employees and customers.

The lesson of all these data, the authors conclude, is that successful criminals study econometrics. "Statistics can help in all walks of life."